We request funds to purchase an Olympus Fluoview 1000 single-point scanning confocal system, which will replace a 10-year-old Bio-Rad MRC 1024 at the Oregon Hearing Research Center (OHRC). The Imaging Core at OHRC, a microscopy resource for the Oregon Health &Science University (OHSU), was built around this single confocal microscope. Because service contracts are no longer available for this confocal and the instrument is starting to fail, we urgently need to replace it. During its useful lifetime, the existing MRC 1024 has been heavily used by a large number of investigators, resulting in at least 100 publications and several journal cover images;the microscope has contributed to an in- crease in the number and quality of grants awarded, has been used to train at least 100 scientists, graduate students, postdoctoral fellows, and international visiting scientists;the instrument has also been critical in recruiting and retaining faculty. Although this old confocal has become unreliable and unserviceable, many grants depend on data acquired with its help. There is no similar instrument at OHSU that could accommodate the time requirements of the 16 participants to this application. After evaluating the Olympus, Zeiss 510 Meta, and Nikon C1si, we selected Olympus because of use of its ability to fluorescence recovery after photobleaching (FRAP) with excellent time resolution;quality of images obtained during demonstrations;its excellent and intuitive graphics interface (essential for a multi-user envi- ronment);adequate local access to service technicians;recommendations from colleagues;and flexibility of the instrument. We propose to acquire an instrument with 405 nm, 488 nm, 559 nm, and 635 nm laser lines, as well as a Simultaneous Illumination Module (SIM) unit for selective bleaching. The research of the primary users of this instrument aims to understand basic mechanisms involved in audi- tion, notably auditory perception at the molecular level, development/morphogenesis of the auditory system, and the processes involved in auditory dysfunction due to administration of life-saving drugs, and/or aging. Because our mission is to provide training, expertise and instrument access not only to OHRC scientists and auditory neuroscience, but also to the entire region regardless of research discipline, this instrument will be of great utility to a wide range of scientific disciplines. A new, functional, state of the art confocal is a necessity for us to fulfill this mission. PUBLIC HEALTH RELEVANCE: The principal focus of the major users of this instrument is on understanding the structure and function of vertebrate auditory and vestibular systems. High-resolution imaging is essential for identification of the molecular architecture of the auditory mechanosensory apparatus, as well as subsequent downstream structures integral to the perception of sound in mammals and humans. In addition, confocal imaging is critical for determining the distribution of ototoxic drugs in the auditory system to determine new strategies for preventing drug-induced deafness.